The intention of this project is to investigate the ability of the human infant to attend to, encode, store, and retrieve perceptual memories for use in altering their perceptual-cognitive interaction with their environment. Typically, infants between 10 and 20 weeks of age are shown a color slide of an unfamiliar object until the infant no longer looks at the stimulus (i.e., has reached a criterion of habituation). Then, a new stimulus, similar to but perceptibly different from the standard, is presented for several trials. Differential attention to the novel versus the familiar stimulus signifies a memory for the standard. Parameters being studied include age, the length of time between the last presentation of the familiar standard and the introduction of the new (i.e., discrepant) stimulus, the magnitude of perceptual discrepancy between the new and the familiar stimulus, the nature of visual stimuli that interfere with memory, and the pattern of looking the infant accords to the repeated presentation of the familiar stimulus (e.g., individual differences in the speed and character of habituation). BIBLIOGRAPHIC REFERENCES: McCall, R.B. Challenges to a science of human behavioral development. In U. Lehr and F. E. Weinert (Eds.), Entwicklung und personlichkeit. Stuttgart: Kohlhammer, 1975, pp. 51-61. McCall, R. B. Commentary on F. D. Horowitz (Ed.), Visual attention, auditory stimulation, and language discrimination in young infants. Monographs of the Society for Research in Child Development, 1975, 39, Ser. No. 158, 132-138.